You need to tell us what you need help with. If you don't have a computer available and your phone is not on zv3, you cannot root at this time. Downgrading to zv3 is mandatory, and the only way to do that is with a computer that you can install drivers and software on. The guide is as explainative as it gets.
If you're not sure if you're on zv3, try to use towelroot. If it works, you're on zv3. If it doesn't, then you aren't.
If you don't know how to tell if you're on zv3, you might want to reconsider rooting.
Why do you want root?